When the flow of oil is restricted, your fork or shock will slowly return to its full travel. The coffee-as-oil analogy holds true here as well. Much like a compression circuit, rebound damping relies on oil moving through a circuit to regulate the speed at which the suspension extends after being compressed. Rebound damping regulates the speed at which your fork or shock recovers, or bounces back, from an impact and returns to its full travel. So now we’re at the point in the movement where your suspension has compressed, so it’s done half of its job. Remember that your bike’s suspension is more than just a spring. Rebound and compression adjustments on Fox and RockShox shocks Josh Patterson / Immediate Media Having your suspension positioned in the open position is useful while descending, and when riding technical terrain, where traction is paramount. When your suspension is open, the flow of oil through the compression damper is unrestricted and it will compress freely to absorb impacts. Turning these knobs and/or dials will gradually restrict the flow of oil through the compression circuit, thereby making your suspension firmer under compression. Both Fox and RockShox use blue to denote compression adjustments on their forks and shocks. On many suspension forks and shocks, compression damping takes the form of a dial and a lockout lever. So what does all this coffee talk translate to on the trail? If diagrams of compression or rebound circuitry make your eyes glaze over, just think of them has a French Press: more holes mean it is easier to compress, while fewer holes would make it harder for you to compress the plunger, i.e., your fork or shock Josh Patterson / Immediate Media Finally, if the plunger didn’t have any mesh openings for the coffee to pass through, it wouldn’t be possible to compress the plunger - you would be “locked-out” of your coffee. Conversely, if there were fewer mesh openings, it would require more force to press the plunger down. If there were more mesh openings you would be able to press down with less effort. Think of the compression circuit as being a French press for coffee. When you apply pressure, the fluid - or coffee - moves through the mesh filter. What’s a compression circuit, you ask? Well the exact mechanics of it will differ by make and model, but in general, a compression circuit is composed of small metal plates, called shims, as well as ports, designed to regulate the flow of oil. This oil circulates through a compression circuit, and by restricting its flow, the suspension can be made firmer and can even be completely locked out. Compression damping is achieved with fluid, usually oil. Why compression damping is a bit like a coffee filterĬompression damping regulates the force that moves a fork or shock through its travel. There are two types of damping: compression and rebound. That’s not what we want.ĭamping means controlling the movement of a spring. Without damping, your fork and shock would be little more than a pair of pogo sticks bouncing uncontrollably off every rock and root and flipping you over the handlebar. There are various ways in which suspension designers adjust these behaviours to suit their intended purposes, and there are certainly pros and cons to air and coil suspensions, but for now we’ll leave it at this: air and coils are both effective means of creating a spring.īut suspension is not just a spring. Conversely, an air spring becomes progressively firmer as it is compressed. A spring can be constructed from coiled metal, just like a mattress spring, or from a gas, usually air, inside of a sealed chamber.Ī coil spring feels linear, meaning the amount of force required to get it to move is consistent throughout the entire range of travel. In its most basic form, suspension starts with a spring.
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